The present invention relates to vehicle seat assemblies and in particular to vehicle seat assemblies having a linear actuator for use in a seat adjuster and/or a seat back recliner.
Manually adjustable vehicle seat assemblies typically include an adjuster for adjusting the fore and aft position of seat assembly relative to the vehicle and often a recliner for adjusting the inclination of the seat back. Such mechanisms must be capable of withstanding the loads applied to the seat assembly during a vehicle collision without an undue amount of seat travel.
To increase seat belt comfort, vehicle seat assemblies are being developed with the seat belts mounted directly to the seat assembly rather than being mounted to the vehicle structure. When the seat belts are mounted to the seat assembly, the seat belts are moved with the seat assembly during seat adjustment, rather than remaining stationary while the seat assembly is moved. This improves passenger comfort and facilitates vehicle assembly. However, with the seat belts mounted to the seat assembly, the forces applied to the recliner and adjuster mechanisms during a vehicle collision are significantly increased.
The above referenced parent patent application discloses a linear actuator which can be used as a seat adjuster or as a recliner and withstand the above mentioned seat belt loads.
The present invention, on the other hand, pertains to an improved linear actuator in which the total number of components is reduced and the actuator assembly is facilitated. The linear actuator of the present invention includes a first part attached to a first seat assembly component in the form of a lead screw with an external helical screw thread. A second part of the actuator is attached to a second seat component movable relative to the first seat component. The actuators second part includes an spin nut threaded onto the lead screw and a housing capturing the spin nut. Angular contact bearings are positioned between the spin nut and the housing, enabling the nut to rotate relative to the housing and axially capturing the nut within the housing.
A clutch at one end of the housing is axially movable between a lock position engaging one end of the spin nut to prevent rotation of the nut and a release position in which the spin nut is freed for rotation. The clutch and the spin nut include radially extending teeth that engage with one another when the clutch is in the lock position to prevent rotation of the spin nut. Axial movement of the clutch is controlled by a cam engaging an outer surface of the clutch to hold the clutch in the lock position. A spring within the housing urges the clutch away from the lock position when such motion is permitted by the cam. A cam release is provided to selectively release the cam and clutch to enable spin nut rotation. The housing is made of two housing half members joined together around the spin nut and bearings, thus facilitating assembly of the mechanism.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.